Discovering wind droughts and their impacts on energy supply
As wind energy continues along its upward trajectory, gradually becoming a crucial global energy source, identifying the regions with the greatest potential for future development is key. However, understanding wind variability and identifying areas susceptible to “wind droughts” can inform where we should develop the industry and how to make it more resilient.
Over the course of 2021 countries in Northern Europe experienced abnormally low wind intensity which led to wide ranging impacts on the industry. Companies operating in the area generated less power than previously forecasted, affecting both the profitability of their operations and the perceived reliability of wind energy in general. For example, British energy company SSE reported producing around 32% less renewable power between April and September due to a dry and low-wind summer, which was the least windy in the UK and Ireland in seventy years.
Although researchers were able to monitor and assess the impacts of wind speed anomalies on power generation, this unexpected variability in wind intensity revealed the need for more information on when and where wind droughts may occur.
Enrico Antonini, researcher at the RFF-CMCC European Institute on Economics and the Environment, is the lead author of a new study that looks to “identify what regions are most affected by these variabilities in wind and therefore where it is most convenient to install wind turbines.” The study, published in the journal Communications Earth & Environment, coined the use of the term wind droughts to describe those periods in which significantly reduced wind speeds occur in areas that are otherwise known for their strong winds.
As the share of global renewable power generation continues to increase, monitoring and predicting wind variability will become ever more important. “To have reliable energy you need a reliable system that is able to predict when and where there will be instances of variability and put in place adequate structures that can help deal with these,” says Antonini. “The more we turn to renewables the more this whole system becomes important and the issue of wind droughts really highlights the intermittent nature of wind energy and how to deal with it.”
What is the current and future role of wind energy generation?
Wind energy is one of the renewable energy sources on which we will increasingly need to rely on for the decarbonization of our energy systems. However, one of the disadvantages of this source of energy is its variability. Furthermore, the more we depend on wind the more we are exposed to its variability both on an annual but also seasonal timescale. This is an issue that is gaining more and more attention and which will increasingly inform how we plan and develop our future energy system and decide how we source the energy we need for our everyday uses.
In what ways does variability and intermittency manifest itself when it comes to wind energy?
In 2021 Europe experienced a phenomenon whereby there was a strong reduction in wind energy generated due to a lower than average annual mean wind speed for that given period. This caused widespread issues for a variety of companies operating in the North Sea area as they were no longer producing as much energy as they expected. We therefore decided to study the variability of wind and what we came to define as wind droughts.
We conducted a global analysis to identify what regions are most affected by these variabilities in wind and therefore where it is most convenient to install wind turbines. We studied both the seasonal variability, and therefore how much wind intensity changes between seasons, and the meteorological variability, which refers to how much it changes from year to year over the same period. By looking at these instances of variability we were able to establish what regions are more subject to variability and ones that have more stable wind.
By doing this we identified areas that experienced wind drought and we looked at the effect of multiple instances of wind drought in the same areas, as the combined effect can have a bigger impact on wind energy production. Our results show that the regions that are less subject to wind droughts are the American Midwest, parts of Australia, South America and the Sahara.
Has wind energy been developed in the places that are most suited for wind energy production?
According to the high potential areas we identified, Africa and parts of Asia are certainly underdeveloped in terms of wind energy potential. On the other hand there are areas such as Northern Europe that are over exploited as there is a high level of variability and are subject to instances of wind drought compared to other areas. That is not to say that wind in Northern Europe isn’t strong during much of the year, but its variability causes problems when it comes to integrating wind energy into our existing energy system.
Why is this variability an issue?
Imagine you have to supply energy to a hospital and you have to choose between solar, wind or a thermal power station, you would have to choose the latter even if it comes with the issue of high emissions as it will produce energy reliably. If you rely on energy sources that depend on the weather you are subject to variability and therefore you need stocking and storage systems such as batteries, hydrogen or other backup and reserve systems.
To have reliable energy you need a reliable system that is able to predict when there will be instances of variability and put in place adequate systems that can help deal with these. The more we turn to renewables the more this whole system becomes important.
The issue of wind droughts really highlights the intermittent nature of wind energy and how to deal with it.
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